The molecular dynamics and melting transition of the confined ibuprofen in titania nanotube studied by NMR

C-13 NMR is employed to study the correlation between molecular dynamics and melting transition for the bulk ibuprofen and the confined ibuprofen in titania nanotubes. Under confinement, for all methyl-groups rotation remains unchanged and aromatic-ring flipping is slightly accelerated. The bulk ibuprofen melts at 351 K activating rapid molecular reorientation and rapid rotation of isobutyl-group while the confined ibuprofen completely becomes 'liquid-like' at 339 K activating also rapid rotation of isobutyl-group and restricted molecular reorientation. It suggests that confinement substantially changes the segmental dynamics which participates in melting transition but only slightly affects the others. (c) 2008 Elsevier B.V. All rights reserved.